18 Devonshire Street
London
W1G 7AQ
info@londonurologyspecialists.co.uk
Stone Clinic
Kidney Stones
Kidney stones affect 1 in 10 people during their lifetime. Our specialist stone clinic offers rapid diagnosis and the full range of modern treatment options.
Clinically Reviewed By
Mr Alberto Coscione
Consultant Urological Surgeon · Reviewed June 2026 · Review due June 2027
What Are Kidney Stones?
Kidney stones (renal calculi) are hard mineral deposits that form inside the kidneys when the urine becomes supersaturated with certain minerals and salts. These substances crystallise and gradually accumulate into a solid mass that can range in size from a tiny grain of sand to a golf ball.
Kidney stones are extremely common, affecting approximately 1 in 10 people at some point during their lifetime. They are more common in men than women and tend to peak between the ages of 30 and 60. The incidence of kidney stones has been rising in recent decades, likely related to dietary changes, obesity, and climate factors.
Many kidney stones are small enough to pass through the urinary tract on their own without causing any symptoms at all. However, when a stone becomes lodged in the ureter (the narrow tube connecting the kidney to the bladder), it can cause renal colic — often regarded as one of the most severe forms of pain a person can experience.
The key to effective management lies in accurate diagnosis, prompt pain relief, and choosing the most appropriate treatment based on the stone's size, location, and composition. At London Urology Specialists, our dedicated Stone Clinic offers the full range of modern diagnostic and treatment options.
Stones can be silent
Not all kidney stones cause symptoms. Most are discovered incidentally on scans performed for other reasons. Stones that sit quietly within the kidney may not require any treatment but should be monitored, as they can grow over time or eventually move into the ureter and cause acute obstruction.
Risk Factors
Low fluid intake
The single most important modifiable risk factor
Family history of kidney stones
Significantly increases lifetime risk
Obesity and metabolic syndrome
Associated with uric acid and calcium stone formation
High sodium and animal protein diet
Increases urinary calcium and uric acid excretion
Certain medications
Including topiramate, indinavir, and calcium/vitamin D supplements
Anatomical abnormalities
Medullary sponge kidney, horseshoe kidney, PUJ obstruction
Inflammatory bowel disease
Malabsorption increases oxalate absorption and stone risk
Hyperparathyroidism
Elevated calcium levels leading to calcium stone formation
Types of Kidney Stones
Kidney stones are classified by their chemical composition. Identifying the stone type is essential because it guides both treatment and long-term prevention strategies.
Calcium Oxalate
Most common typeThe most common type by far. They form when calcium combines with oxalate in the urine. High dietary oxalate (spinach, nuts, chocolate), low fluid intake, and certain metabolic conditions increase risk. They appear dark or brown on scans and are typically hard and spiky.
Calcium Phosphate
Less commonOften occur in combination with calcium oxalate. They are associated with higher urinary pH (alkaline urine) and may be linked to conditions such as renal tubular acidosis or hyperparathyroidism although there is often no metabolic abnormality found. They tend to be smoother and paler than oxalate stones.
Uric Acid
~5-10% of stonesStrongly associated with gout, high-protein diets, obesity, and diabetes. They form in acidic urine (low pH) and are unique because they are radiolucent — invisible on plain X-ray but visible on CT scan. Uric acid stones are the only stones that can sometimes be dissolved with urinary alkalinisation using certain medications.
Struvite (Infection Stones)
Can become staghornCaused by urinary tract infections with specific strains of bacteria (e.g. Proteus). They can grow rapidly and fill the entire collecting system of the kidney, forming large branching "staghorn" calculi. Struvite stones require both surgical removal and treatment of the underlying infection.
Cystine
Rare, hereditaryCaused by cystinuria, an inherited genetic condition where the kidneys excrete excessive amounts of the amino acid cystine. Cystine stones typically present in younger patients (teens and twenties) and tend to recur frequently. Management requires aggressive hydration, urinary alkalinisation, and sometimes medications.
Symptoms of Kidney Stones
The symptoms of kidney stones depend on the stone's size, location, and whether it is causing obstruction (blockage of the urinary flow). Small stones in the kidney may produce no symptoms at all. Symptoms typically begin when a stone moves into the ureter and causes a blockage.
Renal Colic
- › Severe, sudden-onset flank or loin pain
- › Pain radiates from back to groin and inner thigh
- › Comes in intense waves (colicky pattern)
- › Often described as the worst pain imaginable
Associated Symptoms
- › Haematuria (blood in the urine)
- › Nausea and vomiting
- › Urinary frequency and urgency
- › Burning on urination (dysuria)
- › Restlessness — inability to get comfortable
EMERGENCY: Fever with Stone Pain
If you have kidney stone pain combined with fever, rigors (shaking chills), or feeling generally unwell, this may indicate an infected obstructed kidney (pyonephrosis) — a urological emergency that can rapidly progress to life-threatening sepsis.
Do not wait for an outpatient appointment. Go to A&E immediately or call 999. Emergency decompression of the kidney with a nephrostomy tube or ureteric stent may be required.
How Are Kidney Stones Diagnosed?
Accurate imaging and blood/urine tests are essential to confirm the diagnosis, determine stone size, location, and composition, and guide treatment planning.
CT KUB
Gold StandardNon-contrast CT scan of the kidneys, ureters, and bladder. It uses multiple X-ray beams to detect all stone types (including uric acid stones invisible on X-ray). It shows stone size and location precisely and reveals other details such as hydronephrosis (swelling of the kidneys). Although it carries a small amount of ionising radiation (roughly just above the background annual radiation exposure in the UK) it is fast, accurate, and the first-line investigation for suspected renal colic.
Ultrasound
No radiation exposure — preferred in pregnancy and for monitoring known stones. Can detect hydronephrosis (swelling of the kidney) and larger stones but may miss smaller stones and those in the ureter. It also tends to make small stones appear bigger, and large stones appear smaller. Often used as a first-line investigation alongside an X-ray KUB.
X-ray KUB
A plain abdominal X-ray can identify radio-opaque stones (calcium-containing) but will miss uric acid and cystine stones. Useful for tracking known radio-opaque stones during follow-up with lower radiation exposure than from a CT scan.
Blood & Urine Tests
Blood tests assess renal function (creatinine/eGFR), calcium, urate, and inflammatory markers. Urine dipstick and microscopy check for haematuria and infection. After a stone has been passed or removed, stone analysis provides the definitive stone type which can help prevention planning.
Treatment Options
Treatment depends on the stone's size, location, composition, and whether it is causing obstruction or infection. At London Urology Specialists, we offer the full range of options from conservative management to advanced surgical intervention.
NICE Treatment Guidance by Stone Size
<5mm
Observe — likely to pass spontaneously
5–10mm
MET or intervention depending on location
10–20mm
ESWL or ureteroscopy
>20mm
PCNL recommended
These are general guides — treatment is individualised based on stone location, composition, symptoms, and most importantly patient factors. Source: NICE guideline NG118.
Conservative Management
Stones <5mmMost stones smaller than 5mm will pass spontaneously within 2-4 weeks. Conservative management is the first-line approach for small, uncomplicated stones without signs of infection.
Pain Relief
NSAIDs (diclofenac) are the gold standard for renal colic pain. Paracetamol and opioids may also be used. Diclofenac also reduces ureteric inflammation. NSAID medications should always be taken with plenty of fluids and on a full stomach, and medical advice should be sought for courses longer than 48hrs.
Hydration
Adequate oral fluid intake helps flush the stone through the system. However, forced overhydration is not recommended during acute colic.
Medical Expulsive Therapy
Tamsulosin (an alpha-blocker) relaxes the smooth muscle of the ureter, and some evidence suggests it may increase the likelihood and speed of spontaneous stone passage. NICE recommends MET primarily for distal ureteric stones between 5–10mm, with a trial of up to 4 weeks before considering intervention.
ESWL (Shockwave Lithotripsy)
Stones <2cmExtracorporeal shockwave lithotripsy uses focused sound waves delivered from outside the body to fragment kidney stones into smaller pieces that can then pass naturally in the urine. It is a non-invasive, outpatient procedure and is usually performed with tablet pain relief or more rarely with light sedation.
Best suited for: kidney stones up to 2cm and proximal ureteric stones. Less effective for very hard stones (e.g. calcium oxalate monohydrate, cystine) and for stones in the lower pole of the kidney where drainage is poor. Multiple sessions may be needed.
Flexible Ureteroscopy & Laser
Most common surgical optionA thin, flexible telescope is passed through the urethra and bladder into the ureter and up to the kidney. The stone is visualised directly and fragmented using a holmium laser. The fragments are either removed with a tiny basket or left as fine dust to pass naturally.
Advantages: No incisions, high stone-free rates, can treat stones anywhere in the ureter or kidney, allows stone fragment retrieval for analysis. A temporary ureteric stent is usually placed for a few days to two weeks after the procedure to allow the ureter to heal.
PCNL (Percutaneous Nephrolithotomy)
Large stones >2cmFor large kidney stones (greater than 2cm), staghorn calculi, or stones that have failed other treatments, PCNL is the procedure of choice. A small keyhole incision (approximately 1cm) is made in the back, and a telescope is passed directly into the kidney through the skin.
The stone is fragmented using ultrasonic, pneumatic, or laser energy and the fragments are suctioned out. PCNL provides the highest stone-free rates for large stones and is performed under general anaesthesia with a typical hospital stay of 1-2 nights. Mini-PCNL uses even smaller access tracts for faster recovery.
Robotic / Laparoscopic Surgery
Rare, complex casesIn rare and complex situations — such as very large stones associated with anatomical abnormalities (e.g. pelvi-ureteric junction obstruction), failed previous procedures, or stones in unusual locations — robotic-assisted or laparoscopic surgery may be required. This allows direct access to the stone while simultaneously correcting the underlying structural problem.
Preventing Recurrence
Without preventive measures, approximately 50% of stone formers will have a recurrence within 5 to 10 years. A tailored prevention strategy can dramatically reduce this risk.
Metabolic Testing
A 24-hour urine collection is the cornerstone of metabolic evaluation. It measures urine volume, calcium, oxalate, uric acid, citrate, sodium, and pH. The results identify specific metabolic risk factors that can be targeted with dietary changes or medication.
Hydration
The single most important preventive measure. Aim for 2.5-3 litres of fluid per day, enough to produce at least 2 litres of urine. Water is best. Lemon water may provide additional benefit through citrate content. Spread intake throughout the day, including before bed.
Dietary Advice
Tailored to the stone type. For calcium oxalate: reduce high-oxalate foods (spinach, rhubarb, nuts), maintain normal calcium intake (do not restrict), moderate salt and animal protein. For uric acid: reduce purine-rich foods and red meat. For cystine: very high fluid intake and urinary alkalinisation.
Medications
Potassium citrate: raises urinary citrate (a natural stone inhibitor) and pH. Thiazide diuretics: reduce urinary calcium excretion. Allopurinol: lowers uric acid levels. The choice depends on the metabolic abnormality identified on 24-hour urine testing.
Follow-up imaging: Regular imaging (usually ultrasound or low-dose CT) is recommended to monitor for new stone formation or growth of residual fragments. The frequency depends on stone activity and individual risk factors — typically every 6-12 months initially, then annually.
Meet your Specialists
Assessment and treatment of kidney stones is led by our experienced consultant urologists. Your care will be personally overseen by one of our senior specialists.
Key Takeaways
Kidney Stones — What You Need to Know
Fever + stone pain = emergency — attend A&E immediately.
- ✓ Kidney stones are very common (1 in 10 people) and highly treatable
- ✓ Most small stones (<5mm) pass on their own with pain relief and hydration
- ✓ CT KUB is the gold-standard investigation for rapid, accurate diagnosis
- ✓ Modern treatments (laser, shockwave, PCNL) are highly effective and minimally invasive
- ✓ Metabolic testing and lifestyle changes can dramatically reduce recurrence
Further Reading — BAUS Patient Information
Need Expert Help With Kidney Stones?
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